SARS-CoV-2 Antibodies Protect People from Infection or Reinfection

Posted by Ella Bette on March 29th, 2021

At the beginning of 2020, the world woke up to a deadly pandemic that ravaged every country, forming a global pandemic and imposing a heavy burden on public health, society, and the economy. Over 118 million individuals have been infected with severe acute respiratory syndrome coronavirus 2 (abbreviated as SARS-CoV-2), of which more than 2.6 million have died and more than 94 million have survived to date. The World Health Organization (WHO) officially named the disease caused by SARS-CoV-2 as COVID-19 on February 11, 2020.

COVID-19 is highly contagious and spreads through infected droplets, affecting a person's respiratory system. The mode of transmission is through coughing, sneezing, or contact with infected surfaces. Preventive measures include keeping social distance, avoiding physical contact and shaking hands. Face masks were introduced to cover the nose and mouth in public places. Other measures taken by the government include 14 days of quarantine, isolation, testing and hand washing. People live in a state of stress and fear, hoping that there is a way to eliminate the disease and return to normal life.

In previous cases, antibodies in humans have proven to be effective in preventing and fighting infections. Antibodies bind to the surface structures of bacteria or viruses, preventing them from replicating. Therefore, one strategy to combat the disease is to produce effective antibodies in large quantities and inject them into the patient, which can lead to recovery rapidly. However, the complex structure, high cost and long production time of antibodies make it difficult for direct injection to be widely used.

Antibodies, which the body creates in response to infection, linger in the blood plasma for several weeks or months, but their levels significantly drop with time. So the presence of antibodies indicates that a person has been infected with SARS-CoV-2 or has been vaccinated against COVID-19. Since the outbreak of COVID-19, hundreds of SARS-CoV-2 antibody research and development projects have been carried out using different strategies, and some achievements have been made. Last year, researchers at the University of Washington School of Medicine and the University of Iowa developed a novel mouse model of SARS-CoV-2 infection that revealed the protective effect of neutralizing antibodies, speeding up the testing and deployment of therapeutic drugs and vaccines. Now, COVID-19 vaccination is being administered.

According to the U.S. Federal Vaccine Adverse Event Reporting System (VAERS), at least one hundred people died after being vaccinated with experimental vaccines. Those who have had no adverse reactions to the vaccine want to know, once we have antibodies, are we safe?

A recent study found that people with SARS-CoV-2 antibodies may have a low risk of future infection. There is evidence that people who have previously been infected with SARS-CoV-2, the virus that causes COVID-19, seem to be well protected against reinfection, at least for a few months. And actual data and cases show that infection after vaccination is extremely rare.

However, a new study published in Nature on March 8, 2021, pointed out that current vaccines and therapies may be less effective at neutralizing new SARS-CoV-2 variants. Usually, after vaccination, the immune system will respond and produce antibodies to neutralize the virus. Against the U.K. and South Africa variants, most antibodies were still effective, although the activity of antibodies in development was modestly weakened. Therefore, Scientists believe that new research on large-scale SARS-CoV-2 antibody screenings is important as the base data to support clinical trials.

Notably, antibodies are still intended as a strong weapon in protecting people from infection or reinfection of SARS-CoV-2. Because the spikes on the SARS-CoV-2 virus that causes COVID-19 change shape, this gave scientists new insights. Antibodies can recognize these different shapes and block the virus, as well as inform the design of vaccines and antiviral therapies. Thus, antibodies are, of course, the focus of research.